MADISON - The articles of impeachment that were being prepared against Richard Nixon before he resigned included obstruction of justice. Obstruction of justice was also the key charge in the impeachment of Bill Clinton.

On Thursday, the Trump Administration -- and even the president himself -- bragged that the firing of James Comey was intended to end the investigation into the Trump campaign’s ties to Russian intelligence operations in the 2016 U.S. election.

Does Trump’s admission amount to impeachable obstruction of justice? We must have a special prosecutor leading an independent investigation to find out.

There are so many questions about Trump’s behavior and the legitimacy of the 2016 election that, in a sense, it’s not surprising to see an illegitimately elected president behaving without legitimacy. But we can’t lose sight of the bigger fight here.